/*****************************************************************************
 Excerpt from "Linux Programmer's Guide - Chapter 6"
 (C)opyright 1994-1995, Scott Burkett
 ***************************************************************************** 
 MODULE: semstat.c
 *****************************************************************************
 A companion command line tool for the semtool package.  semstat displays
 the current value of all semaphores in the set created by semtool.
 *****************************************************************************/
/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * See the COPYING file for license information.
 */

#if HAVE_CONFIG_H
#  include "config.h"
#endif

#include "common.h"

#if HAVE_SYS_IPC_H
#  include <sys/ipc.h>
#endif
#if HAVE_SYS_SEM_H
#  include <sys/sem.h>
#endif

/* arg for semctl system calls. */
union semun {
  int val;			/* value for SETVAL */
  struct semid_ds *buf;		/* buffer for IPC_STAT & IPC_SET */
  ushort *array;		/* array for GETALL & SETALL */
  struct seminfo *__buf;	/* buffer for IPC_INFO */
  void *__pad;
};

int get_sem_count(int sid);
void show_sem_usage(int sid);
int get_sem_count(int sid);
void dispval(int sid);

int main(int argc, char *argv[])
{
        key_t key;
        int   semset_id;

        /* Create unique key via call to ftok() */
        key = ftok(".", 's');

        /* Open the semaphore set - do not create! */
        if((semset_id = semget(key, 1, 0666)) == -1) 
        {
                printf("Semaphore set does not exist\n");
                exit(1);
        }

        show_sem_usage(semset_id); 
        return(0);
}

void show_sem_usage(int sid)
{
        int cntr=0, maxsems, semval;

        maxsems = get_sem_count(sid);

        while(cntr < maxsems) {
                semval = semctl(sid, cntr, GETVAL, 0);
                printf("Semaphore #%d:  --> %d\n", cntr, semval);
                cntr++;
        }
}

int get_sem_count(int sid)
{
        int rc;
        struct semid_ds mysemds;
        union semun semopts;

        /* Get current values for internal data structure */
        semopts.buf = &mysemds;

        if((rc = semctl(sid, 0, IPC_STAT, semopts)) == -1) {
                perror("semctl");
                exit(1);
        }

        /* return number of semaphores in set */
        return(semopts.buf->sem_nsems);
}

void dispval(int sid)
{
        int semval;

        semval = semctl(sid, 0, GETVAL, 0);
        printf("semval is %d\n", semval);
}